Integrated circuits are formed at the face of a semiconductor wafer. It is usual to form a large number of integrated circuits on the wafer at the same time. In the instance where the integrated circuits, or groups of them, are identical to each other, it has become common practice to use a reticle for imaging various masking, etching and deposition steps in the fabrication of the integrated circuit. The reticle is "stepped" from location to location on the semiconductor wafer such that identical integrated circuits or groups of integrated circuits are formed. This saves the considerable expense and technical problems involved in designing and using a set of masks for the entire semiconductor wafer surface.
More recently, it has become common practice to fabricate several integrated circuits, which may or may not be identical to each other, within one reticle area. In the instance where integrated circuits are identical to each other, defects can be present in certain of the integrated circuits formed within a single reticle area that are not present in the other circuits in the reticle area. These differences in defect occurrence can result in different quality and reliability characteristics. Because these differences exist, it would be useful to keep a record of which field location, or position within the reticle, an integrated circuit came from.